Punishing Syria

When a government viciously attacks its own citizens with weapons of mass destruction, killing or injuring hundreds of innocent men, women and children, its actions represent a violation of long-established international norms that the world cannot ignore. That is the situation now facing President Barack Obama following reports last week that chemical weapons were used against residents of a rebellious Damascus neighborhood. As Secretary of State John Kerry made clear in his televised statement this afternoon, there is now little if any doubt that the Syrian government has carried out crimes against humanity that demand a clear and forceful response from the U.S. and its allies.

President Obama long ago warned Syria's embattled President Bashar Assad that any use of his military's chemical weapons against rebels trying to topple his regime would cross a "red line" prompting a strong U.S. reaction. Earlier this year, after U.S. and foreign intelligence agencies reported that Mr. Assad's forces probably had conducted "limited" attacks against civilians last year using deadly sarin gas, Mr. Obama reacted by authorizing limited arms shipments to some Syrian opposition groups, though not as much as the rebels wanted or needed.

But the chemical attacks that the U.S. believes were carried out by Syria's military last Wednesday appear to have been altogether larger, more indiscriminate and far more deadly than the ones reported earlier. Opposition groups distributed horrific images of scores of bodies of civilians, including women and children, whom they claim were killed in the attack. Meanwhile, the French charity Doctors Without Borders said its workers witnessed hundreds of victims brought to a local hospital suffering from severe convulsions, respiratory disorders and other symptoms consistent with exposure to sarin nerve gas.

Given the overwhelming evidence of a massacre, the Obama administration hardened its rhetoric over the weekend, with unnamed officials quoted as saying the president no longer doubted that a stronger, more direct military response was required to deter Mr. Assad from using such weapons again. Tellingly, U.S. officials brushed off offers from the Syrian government to allow United Nations inspectors to visit the site this week, saying Mr. Assad had lost all credibility by delaying their access to the area until crucial evidence had been destroyed. The question now appears to be when and how — rather than whether — the U.S. will intervene to punish the Assad regime.

That response must be measured but unambiguous as a statement of U.S. resolve. Ideally, it would target Syria's chemical weapons storage depots, delivery systems and military command and control centers while avoiding densely populated areas that carry the risk of significant civilian casualties. Republican Sens. John McCain of Arizona and Lindsey Graham of South Carolina have called for cruise missile strikes on Syria's military airfields and air defense systems as well, to create a no-fly zone over the country and allow opposition fighters to set up havens where they could train and regroup. The Pentagon reportedly has prepared a range of options from which the president could choose, presumably including the possibility of deploying Special Forces units on the ground to secure and destroy Syria's chemical weapons arsenal.

Mr. Obama has rightly been wary of any deeper U.S. military involvement in Syria, not least because there's no guarantee that whatever government eventually replaces Mr. Assad will be any more friendly to American interests in the region than he is. The president is also mindful of the fact that after the decade-long wars in Iraq and Afghanistan, the American public has little appetite for jumping into another messy Middle East conflict that has the potential to end equally badly and at a similar cost in blood and treasure.

But there comes a time when the U.S. has no choice but to exercise its moral leadership and military might to enforce basic norms of international behavior that, if allowed to lapse, risk plunging the world into anarchy. Mr. Obama should seek a U.N. resolution authorizing the use of force to prevent Mr. Assad's use of chemical weapons, but if that fails — as is likely, given the opposition of veto-wielding Security Council members Russia and China — he should work closely with Britain, France, Germany and others (including, we hope, some Arab allies) in a new coalition committed to holding Mr. Assad to account for his crimes.

Mr. Assad, as well as the leaders of other rogue states, especially Iran and North Korea, needs to be shown that certain behaviors by governments will not be tolerated. The sooner they get that message, the better off the U.S. and the world will be.